Adding a list in Service Mananger Query Filter

Question

In this post:
http://www.concurrency.com/blog/service-manager-request-query-result-filtering/
" The trick was to setup the simple list to include no initial results, which provided very fast form load and quick search
result return speeds. "
They have a list or a prompt in their query filter. Is there a site anywhere that explains what this is, or where to do this? I'm absolutely baffled and searching provides no documentation but sky-high level overviews. 

Answer 1

Lets say you want to filter users based on department. You'll end up with two questions in your service offiering
Department to search in. refresh the next question after changing this value.
User.
the first question contains a simple list (see the table at
This Blog Post for more details on that)
[null]
LegitDepartment1
LegitDepartment2
LegitDepartment3
ETC...
the second question is your actual query result question. The Criteria on this is going to compare the user's department to the results of the first question. >when the form loads, it going to run the following query:
System.User where Department = [Null]
Since there are no users with a null department, this result will be empty and return immediately. 
Then, the user goes down, hits the right department, and then hits refresh on the second question and gets the correct users, clicks the right one, and goes on with their life.